1. Field
This disclosure relates generally to the field of communications and more specifically to the system and methods for performing multiple inter-technology registrations and handoffs across different radio access networks.
2. Background
Radio access networks (RANs) are widely deployed to provide voice, data and multimedia services to mobile devices. These networks typically differ from each other based on radio access technologies (RATs) they employ. Examples of commonly deployed radio access technologies include: code division multiple access (CDMA) used in CDMA2000 networks, such as 1x, HRPD and eHRPD, wideband CDMA used in the universal mobile telecommunication system (UMTS) networks, time division multiple access (TDMA) used in Global System for Mobile communications (GSM) networks, and frequency division multiple access (FDMA) used in 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) networks. Different RATs usually employ different signal modulation and coding schemes and different communication protocols, they operate in different frequency bands and provide different quality of service (QoS).
Due to the large variety of RANs currently deployed worldwide, popularity of multimode mobile devices capable of supporting multiple RATs has grown significantly. These multimode mobile devices may have one or more radios for communication with multiple RATs. During operation, a multimode device typically searches and registers with an available RAN. The technology with which mobile device currently registered called primary RAT. The device may then periodically search for more-preferred RANs and register with those networks as well in order to subsequently handoff to one of those networks. These technologies are called non-primary RATs. However, due to network differences, performing inter-technology registrations and handoff between a primary and a non-primary RAT are resource intensive and inefficient processes. Accordingly, there is a need to improve registration and inter-technology handoff across different RATs.